In 1939, archaeologists Marion and Matthew Stirling discovered the bottom half of an Olmec stone monument called Stela C with part of a date carved on it. The date showed 16.6.16.18 in the Mesoamerican Long Count calendar, but the first digit was missing. This incomplete date sparked a decades-long archaeological mystery about the true age of the Olmec civilization.

Using a clever indirect argument, the Stirlings guessed the missing digit was 7, placing the date at September 3, 32 BC. This would make the Olmecs much older than the Mayans, a claim many experts initially rejected. The controversy persisted for 30 years until 1969, when a farmer found the other half of the stone and confirmed the Stirlings' guess was correct - the missing digit was indeed 7.

The mystery deepened when considering how the Olmec calendar could be so precise that we can translate their dates to exact Gregorian equivalents. The answer lies in the Mesoamerican Long Count system, which counts days from a creation date of September 6, 3114 BCE. The correlation constant between this system and the Julian Date calendar has been established as 584,283, allowing modern scholars to convert Olmec dates with remarkable accuracy.